This invention relates to control system and, more particularly, to system for preventing theft of a motor vehicle.
Current designs for motor vehicles typically include a mechanical lock combination. The lock is engaged to a mechanical arm of an electrical switch and rotation of the arm, which is enabled by inserting a proper key in the lock and rotating the arm, in turn, enables the electrical systems that operate the vehicle""s ignition. This is insufficient to prevent theft of vehicles because it is possible to gain access to the back of the lock and duplicate the switch connections with xe2x80x9cclipxe2x80x9d leads.
Many patents have been issued to overcome the problem of stolen vehicles, and one recent patent is U.S. Pat. No. 5,861,799, and this patent cites oer two dozen other patents. None of them completely solve the aforementioned problem.
To illustrate, the ""799 patent describes an arrangement where an element is interposed in the lead that normally goes from the ignition switch to circuitry that enables the operation of the vehicle. This element includes keypad 22 that is installed on a vehicle""s dashboard, and a circuit board 36 that determines whether a PIN code that is entered through the keypad is correct. If it is not, the vehicle""s operation is not enabled. The housing in which circuit board 36 is attached to the keypad is sealed so that it cannot be invaded. As depicted in the patent""s FIG. 2, it appears that no access is available to the leads that connect keypad 22 to circuit board 36.
The output of circuit board 36 is provided via a pair of leads 32, which are extended to a solenoid in the vehicle""s fuel tank. Those leads provide current for the solenoid. Specifically, when the correct PIN code is provided, current is caused to flow through leads 32 and the solenoid opens access to the engine""s fuel line. When the correct PIN code is not provided, no current is caused to flow and the solenoid remains in its normal, fuel-off, position.
Alas, this forms a weak link of the system. A thief can easy gain access to leads 32, and a simple severing of leads 32 from housing 34 allows the thief to inject a current and cause the solenoid to engage and allow fuel to flow. Worse than that, one of the benefits that the ""799 patent touts is the ability of a pursuing police vehicle to stop a vehicle""s movement. This ability is enabled by the circuit board""s ability to receive a signal from the pursuing police vehicle. Unfortunately, the above-mentioned approach for a thief to activate the solenoid also nullifies this touted ability.
The problems found in prior art approaches are overcome, and an advance in the art is achieved with an arrangement that relies on other than DC signals to be communicated to at least one operating element of a vehicle that is responsive to electrical signals. More specifically, in accord with the principles disclosed herein, one or more operating elements of a vehicle are integrally manufactured with, or integrally coupled to, a decoder that is responsive to encoded (non-DC) control signals. The encoded signals are generated with an encoder that is activated via a security element such as a keypad. Only when a correct PIN code is presented to the keypad will the encoder be activated and generated the appropriate encoded control signal or signals.